It has been known in the prior art to provide a portable crushing and screening plant in which a plurality of devices for processing material to be crushed are positioned in overlying and discharging relation to a first conveyor, which first conveyor then discharges the material which has been deposited upon it onto a second conveyor which elevates the material being processed and deposits such material through the intermediary of still another conveyor into the upper feed end of an inclined vibrating screening device which classifies the material thus deposited on the vibrating screening device for recirculation and/or for discharge from the screening device as one or more end products of predetermined size. Such an arrangement is shown, for example, by U.S. Pat. No. 2,593,353 issued to Harry J. Shelton, Jr. on Apr. 15, 1952.